This invention relates to a telephone switching apparatus which discriminates the voiceprint of the calling party of a telephone and switches a telephone circuit when the discriminated voiceprint agrees with a specified voiceprint.
As an apparatus of this type, a voice mail system has heretofore been employed. It renders services such as the accumulation and exchange of messages among extension sets and the transmission and reception of messages to and from the calling parties of telephones, additional services for designating methods of handling the messages in association with the first-mentioned services, auxiliary services for efficiently utilizing the voice mail system, and so on.
FIG. 4 is a block diagram showing by way of example a conventional telephone switching apparatus which employs an electronic mail type system illustrated on page 436, in FIG. 2.14 of "Data Communication Handbook" edited by the Japan Society of Electronic Communication. Referring to the figure, a general telephone exchange network, such as a PBX, 1 is connected to a plurality of telephone sets P.sub.1 -P.sub.n. A voice mail system 2 transmits and receives messages between it and the individual telephone sets P.sub.1 -P.sub.n through the telephone exchange network 1, and it is constructed as follows.
A plurality of circuit control units Q.sub.1 -Q.sub.n, which are respectively connected to the telephone exchange network 1 and disposed in correspondence with the telephone sets P.sub.1 -P.sub.n, serve as interfaces to the telephone exchange network 1. A voice processing unit 3 is connected to the circuit control units Q.sub.1 -Q.sub.n and a bus B, and it converts input analog voice information into digital signals. A voice response unit 4, which is connected to the circuit control units Q.sub.1 -Q.sub.n and the bus B and which outputs operational messages according to various processes through the synthesis of voice, to send set phrases to the calling party of the telephone in accordance with a predetermined program. It is made up of an LSI chip commercially available, for example, a channel vocoder or an LPC (linear prediction) vocoder. A central control unit 5 controls the whole voice mail system 2 through the bus B on the basis of a predetermined program. A disk device 6 is connected to the bus B, and it stores therein the predetermined programs, the messages as voice mail generated by the digital conversion in the voice processing unit 3, and so on. Other peripheral devices 7 are connected to the bus B.
The prior-art telephone switching apparatus is constructed as described above. In a mode where it is utilized as an answer phone during the user's absence, the user stores a message for making his/her absence known, in the disk device 6 beforehand. The voice response unit 4 answers to that effect to a calling party during the absence, and a message from the calling party is accumulated in the disk device 6 through the voice processing unit 3. Also, in a mode where the user has registered the telephone number of a place of his/her visit in the disk device 6 beforehand, the telephone circuit of the user's telephone number dialed by a calling party has the telephone number switched to transfer through any of the circuit control units Q.sub.1 -Q.sub.n and is connected to the telephone set at the user's destination, for example, the telephone set P.sub.j not shown.
In this regard, in a case where the user desires the transfer of calls from limited opposite parties only, he/she previously informs the parties of a password. Thus, only when the calling party has input the password through a dialing operation or with a voice signal during the user's absence is the call thereof switched and transferred to the telephone number of the user's destination.
Usually, during these processing operations, operation guidance through synthetic voice is sent to tee calling party through the voice response unit 4.
Since the prior-art telephone switching apparatus is constructed and operated as described above, it has the problem that, when the user has previously registered the telephone number of the destination to be switched to, the call to the user is unconditionally switched and connected to the telephone set of the destination even if the calling party is not one truly desired by the user, or the use of the password intended to prevent the former problem is troublesome and also unnatural.